JP5527123B2 - Fixing device - Google Patents

Description

  The present invention relates to a fixing device.

  An electrophotographic image forming apparatus includes a fixing device. The fixing device heats and presses the pigment (toner) transferred to the paper to fix it. The fixing device includes, for example, a fixing belt carried by two rollers, and a roller (fixing roller) provided at a position facing the fixing roller with the fixing belt interposed between the rollers carrying the belt, And a sheet on which toner is transferred is provided between the contact portion (nip) between the fixing belt and the fixing roller. Further, the fixing belt or the fixing roller is heated. As the sheet passes between the contact portions of the fixing belt and the fixing roller, the toner on the sheet is heated and pressed to perform a fixing process.

Conventionally, the outer peripheral surface of each roller used in a fixing device has a layer (elastic layer) of an elastic material (for example, rubber) (for example, Patent Document 1, Patent Document 2, etc.).
Further, the fixing device is required to suitably remove the sheet subjected to the fixing process from the fixing roller. Therefore, a layer (release layer) that covers the outer peripheral surface of the elastic layer of each roller with a material having a hardness higher than that of the elastic layer (for example, a resin such as tetrafluoroethylene / perfluorovinyl ether copolymer (PFA)). There is a fixing device in which the sheet is easily detached from the fixing roller.

  In addition, there is a fixing device in which the hardness of the outer peripheral surface of the roller facing the fixing roller is made smaller than the hardness of the outer peripheral surface of the fixing roller in order to increase the nip width.

Japanese Patent No. 3654953 Japanese Patent Laid-Open No. 7-139541

  However, in a conventional fixing device, a roller (fixing roller) having a higher outer peripheral surface hardness may damage a roller (a roller facing the fixing roller) having a relatively lower outer peripheral surface hardness. For example, as shown in FIG. 6, at the location where the end of the fixing roller in the direction along the rotation axis of each roller contacts the outer peripheral surface of the opposing roller, the outer peripheral surface of the opposing roller is scraped by the end of the fixing roller. (For example, the damaged portion H shown in FIG. 6).

  Temporarily, in the direction along the rotation axis direction of each roller, the width of one roller is at least larger than the width of the elastic layer of the other roller, and the end portion of one roller in the direction along the rotation axis direction of the other roller When it is made not to contact the outer peripheral surface, the other roller as shown in FIG. 6 is not damaged. However, in this case, for example, as shown in FIG. 7, at the end of the elastic layer of the other roller sandwiched between the core metal of the other roller and the one roller, the elastic layer protrudes in the rotation axis direction, Stress concentration occurs at the interface end portion between the elastic layer and the cored bar, and the elastic layer breaks due to the pressing force at the interface end portion. The breakage at the interface edge may be a cause, and the breakage may proceed to near the center of the elastic layer.

  An object of the present invention is to prevent damage to a roller of a fixing device.

The invention according to claim 1 is a fixing device having a fixing belt carried by at least one roller and a fixing roller pressed against the roller across the fixing belt,
The fixing roller includes a core portion that is rotatably provided, an elastic portion that covers the core portion so as to have a cylindrical shape around the rotation axis of the core portion, and a cylindrical outer peripheral surface of the elastic portion. A release portion covering the core, and an end portion of the elastic portion in the direction along the rotation axis and an end portion of the release portion in the direction along the rotation axis are the core portion of the core portion. Projecting in the direction along the rotation axis with respect to the end portion in the direction along the rotation axis of the portion where the elastic part abuts, and the end portion of the core portion in the direction along the rotation axis is the end The portion side is provided to be inclined toward the rotating shaft side, and the inclined surface and the elastic portion are bonded .

According to a second aspect of the present invention, in the fixing device according to the first aspect, an outer peripheral surface of an end portion of the release portion in a direction along the rotation axis protrudes toward an outer peripheral side of the cylinder. And

According to a third aspect of the present invention, in the fixing device according to the first or second aspect , the end portion of the elastic portion in the direction along the rotation axis is thinned toward the end portion side. It is provided.

According to a fourth aspect of the present invention, in the fixing device according to any one of the first to third aspects, the width of the roller in the direction along the rotation axis is the fixing in the direction along the rotation axis. The width of the fixing roller in a direction along the rotation axis is larger than the width of the roller, and is larger than the width of the fixing belt in the direction along the rotation axis.

A fifth aspect of the present invention is the fixing device according to any one of the first to fourth aspects, wherein the release part is a seamless cylindrical shape.

  According to the present invention, it is possible to prevent damage to the roller of the fixing device.

1 is a diagram illustrating a main configuration of a fixing device according to a first embodiment of the present invention. FIG. 3 is a cross-sectional view illustrating a part of a fixing roller. FIG. 6 is a cross-sectional view showing a part of a fixing roller used in a fixing device according to a second embodiment of the present invention. FIG. 6 is a cross-sectional view showing a part of a fixing roller used in a fixing device according to a third embodiment of the present invention. FIG. 10 is a cross-sectional view showing a part of a fixing roller used in a fixing device according to a fourth embodiment of the present invention. FIG. 10 is an explanatory diagram illustrating an example in which a fixing roller in a conventional fixing device breaks a roller facing the fixing roller. It is explanatory drawing which shows the example in which one roller damaged the edge part of the elastic layer of the other roller in the conventional fixing device.

  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows a main configuration of a fixing device 1 according to the first embodiment of the present invention.
The fixing device 1 includes a belt mechanism 10 and a fixing roller 20.
The belt mechanism 10 includes two rollers 11 and 12 and a fixing belt 13 carried by the two rollers 11 and 12. The two rollers 11 and 12 are provided inside the annular fixing belt 13 and carry the fixing belt 13.

The two rollers and the fixing roller 20 are rotatably supported at a position where the outer peripheral surfaces of the two rollers and the fixing roller 20 are pressed against each other by a support unit (not shown). The rotation axes of the rollers are provided in parallel. In addition, one of the two rollers (for example, the roller 11 shown in FIG. 1) and the fixing roller 20 are provided so as to be in pressure contact with each other with the fixing belt 13 interposed therebetween. Each roller is rotationally driven by a driving unit (not shown). The rotation direction of the fixing roller 20 and the roller 11 provided at a position facing the fixing roller 20 and in pressure contact with the fixing roller 20 is different, and the fixing belt 13 and the fixing roller 20 carried by the rollers 11 and 12 are operated. The sheet passes between the contact portions (nips) between the sheet and the sheet. As a result, the fixing process is performed on the sheet.
In the first embodiment, the diameters (φ) of the rollers 11 and 12 are 90 [mm], the diameter (φ) of the fixing roller 20 is 80 [mm], and the press contact force of the nip is 2000 [N].
The width of the roller 11 in the direction along the rotation axis of each roller is larger than the width of the fixing roller 20 in the direction along the rotation axis, and the width of the fixing roller 20 in the direction along the rotation axis is the fixing belt in the direction along the rotation axis. Greater than 13 widths. Then, both ends of the fixing belt 13 in the direction along the rotation axis are provided so as to be located inside both ends of the fixing roller 20 in the direction along the rotation axis, and both ends of the fixing roller 20 in the direction along the rotation axis are arranged on the rotation axis. Is provided so as to be located inside both ends of the roller 11 in the direction along the direction.

  The roller 11 facing the fixing roller 20 is a roller in which an outer peripheral surface of a core material (for example, metal) is covered with an elastic member (for example, rubber). The elastic member covering the roller 11 of the first embodiment is a rubber having a hardness of 5 [°] measured by a type A durometer defined in JIS K 6249, and the rubber thickness is 20 [mm].

The roller 12 has a heater 14 that heats the roller 12 from the inside. The fixing belt 13 is heated via the roller 12 heated by the heater 14. Further, the roller 12 has a guide portion 15 for preventing the fixing belt 13 from being detached from the rollers 11 and 12.
The fixing belt 13 transmits heat to the sheet passing between the contact portions between the fixing belt 13 and the fixing roller 20. The fixing belt 13 of the first embodiment includes a base portion that is in contact with and supported by the two rollers 11 and 12, and a rubber layer that is provided on the outer peripheral surface of the base portion that does not contact the two rollers 11 and 12. Have The base is made of polyimide (PI), and its thickness is 80 [μm]. The rubber layer has a thickness of 200 [μm]. The rubber layer is coated with PFA on the outer peripheral surface on the side in contact with the fixing roller 20, and the thickness of the PFA layer is 20 [μm].

FIG. 2 shows a cross-sectional view of a part of the fixing roller 20.
The fixing roller 20 includes a core part 21, an elastic part 22, and a release part 23.
Both ends of the core portion 21 are rotatably supported by the aforementioned support portion, and are rotated by the aforementioned drive portion. Although the core part 21 of 1st embodiment is metal, what is necessary is just a raw material which has sufficient intensity | strength which can become a core material of the elastic part 22 and the mold release part 23. FIG.

  The elastic portion 22 is provided so as to cover the outer peripheral surface of the core portion 21 using the core portion 21 as a roller core material, and covers the core portion 21 so as to have a cylindrical shape with the center L of the rotation axis of the core portion 21 as the center. The elastic part 22 of the first embodiment is made of rubber having a hardness of 30 [°] measured by a type A durometer defined in JIS K 6249, and the rubber thickness is 1 [mm].

The release part 23 covers the cylindrical outer peripheral surface of the elastic part 22. The mold release part 23 of the first embodiment is a cylindrical tube that is integrally molded and has no joints, and is provided so that the inner surface of the tube is in close contact with the outer peripheral surface of the elastic part 22. Coating. The mold release part 23 of the first embodiment is made of PFA, and the thickness of the layer forming the cylinder is 30 [μm].
The fixing roller 20 is provided to have a higher hardness than the roller 11 due to the thickness of the elastic portion 22 and the release portion 23.

  The outer peripheral surface of the core portion 21 and the inner peripheral surface of the elastic portion 22 are bonded, and the outer peripheral surface of the elastic portion 22 and the inner peripheral surface of the release portion 23 are bonded.

  The ends of the elastic portion 22 and the release portion 23 in the direction along the rotation axis of the fixing roller 20 are the ends in the direction along the rotation axis of the portion of the core portion 21 where the core portion 21 and the elastic portion 22 abut. It protrudes in a direction along the rotation axis of the fixing roller 20 with respect to the portion (for example, the end portion 21a shown in FIG. 2). In FIG. 2, the edge part (edge part 22a) of the elastic part 22 which protrudes with respect to the edge part 21a and the edge part (edge part 23a) of the mold release part 23 are shown.

  The elastic portion 22 and the release portion 23 receive a pressing force generated when the fixing roller 20 and the roller 11 are pressed against each other. At this time, since the core portion 21 does not exist inside the end portion 22a of the elastic portion 22, the end portion 22a and the end portion 23a bend toward the center L side of the rotation shaft of the fixing roller 20 according to the pressing force. For this reason, the stress at the pressure contact portion between the fixing roller 20 and the roller 11 decreases toward the end of the fixing roller 20. Therefore, the end 23 a of the release part 23 does not scrape the outer peripheral surface of the roller 11.

  The width D1 at which the end portion 22a of the elastic portion 22 and the end portion 23a of the release portion 23 project in the direction along the rotation axis of the fixing roller 20 with respect to the end portion 21a of the core portion 21 is the outer diameter size of the fixing roller 20. Or the thickness of the elastic part 22 and the Young's modulus of the elastic part 22 can be selected as appropriate. However, if the width Dl is too small, the end 23a of the release part 23 is The effect of suppressing the concentration of stress may be reduced, and the outer peripheral surface of the roller 11 may be shaved. On the other hand, if the width Dl is too large, the bent end portion 22a and the end portion 23a receive vibration due to the rotation of the fixing roller 20 to generate a large vibration, thereby generating abnormal noise, or the end portion 22a and the end portion. 23a and the surrounding structure may be destroyed. In the first embodiment, the width Dl is preferably between 3 and 10 [mm].

  As described above, according to the first embodiment, even when the elastic portion 22 and the release portion 23 receive a pressing force due to the fixing roller 20 and the roller 11 being pressed against each other, the end portion 22a of the elastic portion 22 and the release portion. Since the end portion 23a of the projection 23 protrudes with respect to the end portion 21a of the core portion 21, the end portion 22a and the end portion 23a can be bent according to the pressing force without being inhibited by the core portion 21. it can. As a result, the closer to the end 23a, the lower the stress at the pressure contact portion between the fixing roller 20 and the roller 11. For this reason, the end 23a does not scrape the outer peripheral surface of the roller 11. Therefore, in the conventional fixing device, it is possible to eliminate the problem of scraping the outer peripheral surface of the opposing roller, which is caused by the end portion of the outer peripheral surface of the fixing roller being in sliding contact with the outer peripheral surface of the opposing roller, Breakage of the roller of the fixing device can be suitably suppressed.

Further, the fixing roller 20 has a higher hardness on the outer peripheral surface than the roller 11. The width of the fixing roller 20 in the direction along the rotation axis of each roller is smaller than the width of the roller 11, and both ends of the fixing roller 20 in the direction along the rotation axis are inside the both ends of the roller 11 in the direction along the rotation axis. It is provided so that it may be located in. For this reason, in the conventional fixing device, with respect to the width in the direction along the rotation axis direction, the width of one roller having a larger outer peripheral surface hardness is larger than the width of the elastic layer of the other roller having a relatively smaller outer peripheral surface hardness. It is possible to solve the problem that occurs when the end of one roller in the direction along the rotation axis direction is not brought into contact with the outer peripheral surface of the other roller. That is, stress concentration occurs at the interface edge between the elastic layer of the other roller and the metal core sandwiched between the core metal of the other roller and the one roller, and the destruction due to the pressing force at the interface edge of the elastic layer. Will not occur. Therefore, in the first embodiment, breakage of the roller 11 of the fixing device can be suitably suppressed.
Further, the width of the roller 11 in the direction along the rotation axis of each roller and the width of the fixing roller 20 in the direction along the rotation axis are larger than the width of the fixing belt 13 in the direction along the rotation axis, and the fixing in the direction along the rotation axis. Both ends of the belt 13 are provided so as to be positioned inside both ends of the roller 11 in the direction along the rotation axis and inside both ends of the fixing roller 20 in the direction along the rotation axis. Therefore, both ends of the fixing belt 13 in the direction along the rotation axis do not protrude from the contact portion between the roller 11 and the fixing roller 20. That is, it is possible to prevent the both ends of the fixing belt 13 in the direction along the rotation axis from being bent out of the contact portion between the roller 11 and the fixing roller 20.

(Second embodiment)
Next, the fixing roller 20A used in the fixing device according to the second embodiment of the present invention will be described. The same components as those of the fixing roller 20 of the first embodiment are denoted by the same reference numerals, and description thereof is omitted. The fixing device of the second embodiment has the same configuration as that of the fixing device 1 of the first embodiment except that the fixing roller 20 is replaced with the fixing roller 20A.
FIG. 3 is a sectional view of a part of the fixing roller 20A according to the second embodiment of the present invention.
As shown in FIG. 3, the end portion 21a of the fixing roller 20A in the direction along the rotation axis of the core portion 21 is chamfered so that the end portion side is inclined toward the rotation shaft side. And the inner peripheral surface of the elastic part 22 is adhere | attached with the inclined surface of the edge part 21a chamfered.
The elastic portion 22 of the second embodiment has an outer peripheral surface regardless of the outer peripheral surface of the portion that contacts the end 21a of the core portion 21 that is chamfered and the outer peripheral surface of the portion that contacts the core portion 21 that is not chamfered. The surface is provided so as to be substantially parallel to the rotation axis of the fixing roller 20. For this reason, as shown in FIG. 3, the elastic part of the part which contact | abuts the edge part 21a of the core part 21 which was chamfered so that thickness may increase according to the inclination of the edge part 21a of the core part 21 which was chamfered. Is provided.

  According to the second embodiment, the end portion 22 a of the elastic portion 22 and the end portion 23 a of the release portion 23 can be bent toward the core portion 21 side by the inclination provided at the end portion 21 a of the core portion 21. The room expands. In addition, the bending of the elastic portion 22 at the portion that contacts the inclination of the end portion 21a of the core portion 21 corresponds to the degree of bending of the end portion 22a of the elastic portion 22 and the end portion 23a of the release portion 23 when there is no inclination. Since it becomes gentler than that, the deflection of the outer peripheral surface of the portion in contact with the inclination also becomes gentle. For this reason, the stress concentration at the end of the nip in the direction along the rotation axis is further alleviated, and the conventional problem in which the outer peripheral surface of the roller opposite to the end of the fixing roller is further suppressed. be able to.

(Third embodiment)
Next, the fixing roller 20B used in the fixing device according to the third embodiment of the present invention will be described. The same components as those of the fixing roller of the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted. The fixing device of the third embodiment has the same configuration as that of the fixing device 1 of the first embodiment except that the fixing roller 20 is replaced with the fixing roller 20B.
FIG. 4 is a sectional view of a part of the fixing roller 20B according to the third embodiment of the present invention.
As shown in FIG. 4, the outer peripheral surfaces of the end portion 22a of the elastic portion 22 of the fixing roller 20B and the end portion 23a of the release portion 23 have a protruding portion M that protrudes toward the outer peripheral side of the cylinder.

  The protrusion M shown in FIG. 4 is a mountain-shaped protrusion whose cross-sectional shape has an inclination M2 on the end side with respect to the apex M1 of the protrusion M, and an inclination M3 on the opposite side thereof. It is provided so as to go around the outer peripheral surface of 20B.

  According to the third embodiment, the protruding portion M contacts the outer peripheral surface of the roller 11 so that the end portion 22a of the elastic portion 22 of the fixing roller 20B and the end portion 23a of the release portion 23 are on the rotating shaft side of the fixing roller 20B. It is pushed to. For this reason, the end portion 22a and the end portion 23a are more reliably bent toward the core portion 21 when receiving a pressing force due to the fixing roller 20B and the roller 11 being pressed against each other. Therefore, it can suppress more favorably that the edge part 23a scrapes the outer peripheral surface of the roller 11.

  The apex M1 of the fixing roller 20B shown in FIG. 4 protrudes to the outer peripheral side by about 1 [mm] more than the outer peripheral surface that is not the end of the fixing roller 20B. Further, with respect to the direction along the rotation axis of the fixing roller 20B, the width of the inclination M2 is 2 [mm], and the width of the inclination M3 is 3 [mm]. These numerical designs are examples, and can be arbitrarily set. However, the end 22a of the elastic part 22 and the end 23a of the release part 23 are favorably bent toward the core part 21, and more than necessary. It is preferable that the end 22a and the end 23a are not pushed toward the rotation shaft side of the fixing roller 20B.

In the fixing roller 20B of the third embodiment shown in FIG. 4, the end portion 21a in the direction along the rotation axis of the core portion 21 is chamfered and the end portion side is the same as the fixing roller 20A of the second embodiment. It is provided so as to incline toward the rotating shaft. And the inner peripheral surface of the elastic part 22 is provided so that it may contact | abut to the inclined surface of the edge part 21a chamfered.
As in the fixing roller 20 of the first embodiment, the protrusion M may be provided on the fixing roller having no inclination at the end 21a in the direction along the rotation axis of the core portion 21.

(Fourth embodiment)
Next, the fixing roller 20C used in the fixing device according to the fourth embodiment of the present invention will be described. The same components as those of the fixing roller of the first to third embodiments are denoted by the same reference numerals, and description thereof is omitted. The fixing device of the fourth embodiment has the same configuration as the fixing device 1 of the first embodiment except that the fixing roller 20 is replaced with a fixing roller 20C.
FIG. 5 shows a cross-sectional view of a part of the fixing roller 20C according to the fourth embodiment of the present invention.
As shown in FIG. 5, the end 22a of the elastic portion 22 of the fixing roller 20C is provided so that the thickness decreases toward the end.

  According to the fourth embodiment, the end 22a of the elastic portion 22 of the fixing roller 20C is provided so that the thickness decreases toward the end, so that the end 22a and the end of the release portion 23 are provided. 23a is more easily bent. For this reason, the end portion 22a and the end portion 23a are more reliably bent toward the core portion 21 when receiving a pressing force due to the fixing roller 20C and the roller 11 being pressed against each other. Therefore, it can suppress more favorably that the edge part 23a scrapes the outer peripheral surface of the roller 11.

The fixing roller 20C of the fourth embodiment shown in FIG. 5 is similar to the fixing roller 20B of the third embodiment in that the outer peripheral surfaces of the end portion 22a of the elastic portion 22 and the end portion 23a of the release portion 23 are cylindrical. It has the protrusion part M which protrudes to the side. Further, in the fixing roller 20C of the fourth embodiment shown in FIG. 5, the end portion 21a in the direction along the rotation axis of the core portion 21 is chamfered, and the end portion side is the same as the fixing roller 20A of the second embodiment. It is provided so as to incline toward the rotating shaft. And the inner peripheral surface of the elastic part 22 is provided so that it may contact | abut to the inclined surface of the edge part 21a chamfered.
You may provide the edge part 22a of the elastic part 22 of the fixing roller 20 of 1st embodiment, or the fixing roller 20A of 2nd embodiment so that thickness may become thin toward the edge part side.

  The embodiment of the present invention should be considered that the embodiment disclosed this time is illustrative and not restrictive in all respects. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  For example, the release part 23 is not limited to the integrally formed tube shape. For example, the release part 23 formed by applying a PFA coating material to the outer peripheral surface of the elastic part 22 and baking it may be used. The layer of the mold release part 23 by such a PFA coating material is provided so that it may become a thickness of 15-20 [micrometer], for example.

  Further, the roller carrying the fixing belt may be configured to include at least one roller facing the fixing roller. For example, the fixing belt may be carried by three or more rollers, or one or more rollers. The fixing belt may be carried by the fixing member. The heat source for heating the fixing belt may be a roller facing the fixing roller or a fixing member.

  Further, specific design items such as the diameter (φ) of each roller, the nip pressing force, and the material and thickness of the layer covering each roller can be appropriately changed.

  In addition, the fixing roller of each of the above embodiments is a roller that is not directly heated by a heating device such as a heater, but the fixing roller according to the present invention may be heated.

DESCRIPTION OF SYMBOLS 1 Fixing device 10 Belt mechanism 11 Roller 12 Roller 13 Fixing belt 14 Heater 15 Guide part 20 Fixing roller 21 Core part 21a Core part end part 22 Elastic part 22a Elastic part end part 23 Release part 23a End part of release part

Claims (5)

A fixing device comprising: a fixing belt carried by at least one roller; and a fixing roller pressed against the roller across the fixing belt,
The fixing roller includes a core portion that is rotatably provided, an elastic portion that covers the core portion so as to have a cylindrical shape around the rotation axis of the core portion, and a cylindrical outer peripheral surface of the elastic portion. A release portion covering the core, and an end portion of the elastic portion in the direction along the rotation axis and an end portion of the release portion in the direction along the rotation axis are the core portion of the core portion. Projecting in the direction along the rotation axis with respect to the end portion in the direction along the rotation axis of the portion where the elastic part abuts, and the end portion of the core portion in the direction along the rotation axis is the end The fixing device is characterized in that a portion side is inclined to the rotating shaft side, and the inclined surface is bonded to the elastic portion . The fixing device according to claim 1, wherein an outer peripheral surface of an end portion of the release portion in a direction along the rotation axis protrudes toward an outer peripheral side of the cylinder. 3. The fixing device according to claim 1, wherein an end portion of the elastic portion in a direction along the rotation axis is provided such that the thickness thereof decreases toward the end portion. The width of the roller along the rotation axis is greater than the width of the fixing roller along the rotation axis, and the width of the fixing roller along the rotation axis is the width along the rotation axis. The fixing device according to claim 1, wherein the fixing device is larger than a width of the fixing belt. The fixing device according to claim 1, wherein the release part has a seamless cylindrical shape.

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